An Explicit-Implicit Hybrid Solvent Model for Grand Canonical Simulations of the Electrochemical Environment

The development of ab initio methods for atomistic simulations of the electrochemical environment is essential for obtaining a mechanistic understanding of the fundamental reactions. We propose here an explicit-implicit solvent model, SOLHYBRID, that enables grand-canonical ensemble simulations of the electrochemical environment with the popular Vienna Ab initio Simulation Package (VASP), extending its capabilities beyond the commonly used the implicit solvent model VASPSol. We further present a subroutine, TPOT, that allows control of the electrode potential, thereby enabling simulations at constant electrode potential to mimic the experimental electrochemical cell. We demonstrate the key points of our approach for the case of CO2 adsorption on Au(110) in the presence of K+ cation.